When I was looking for a rotavator a gent told me to stay clear of
Briggs and Stratton because they run for 10 minutes and stop. Have to
leave them and let them cool down and then they start. His advice to
me was to get a machine with a Honda engine because they are so
reliable.
Asking around to confirm this and got a few people saying the same
thing.
Unfortuantely Steve you are not the only one to have to suffer this
problem, regretably no simple solution (unless you fancy fitting a
different motor!)

Good luck

Clifford
Bawtry, Doncaster, South Yorkshire